Pipe or flowlines are laid along a sea floor to transport fluid such as oil or gas. At offshore structures the flowline includes an upstanding vertical portion attached to the structure and having an end available above the sea surface for connection to a storage tank, a tanker vessel, or other facilities for storage and distribution of the fluid. Generally speaking, prior proposed riser flowline portions at offshore structures have included a separate pipe portion having a lower end connected to a flowline at the sea bottom by usual pipe interconnecting and coupling devices assembled and installed by divers. In other prior proposed vertical flowline risers "J" tubes were installed during construction of the offshore platform and a flowline was pulled into position by means of a wire line passed through the "J" tube receiver. Such prior proposed arrangements were expensive and time consuming in installation. Since an offshore structure may be a terminal for a plurality of flowlines, the number of flowlines must be accurately predicted when a "J" tube receiver was installed at the time of construction of the offshore structure. Moreover, installations of such prior proposed constructions became proportionately more expensive as the installations were made in deeper and deeper water.
Various devices have been proposed for bending a flowline to provide a selected radius of curvature. In U.S. Pat. No. 3,650,114 a plurality of sleeves are associated with the flowline, each sleeve being connected to a hydraulic cylinder and piston. The cluster of hydraulic cylinders and pistons were used to gradually swing the flowline outwardly from the platform and downwardly so that the flowline would be subjected to bending depending upon the extension of each individual piston and cylinder means. In U.S. Pat. No. 3,531,941 a bending device was mounted on a pipe a selected distance from its end. A cable connected to the bending device was passed through a pulley at the bottom of a derrick leg near the sea floor and then to a winch on the platform so that the bending member and flowline could be drawn toward the bottom of the leg and at the same time subjected to bending, the upper end of the flowline being secured to the platform. In U.S. Pat. No. 3,640,080 a bending device is moved down a rail secured to the platform for bending the flowline, the free end of the flowline being held by the pipe laying vessel. Such prior proposed bending devices were relatively complicated and complex, were expensive to manufacture, and were difficult to operate in order to achieve a precise bending at a precise location.